Blaschko's lines

Last reviewed 04/2022

Blaschko's lines, also called the Lines of Blaschko, are skin lines invisible under normal conditions

• thought to represent pathways of epidermal cell migration and proliferation during the development of the fetus
  
  
• become apparent when some diseases of the skin or mucosa manifest themselves according to these patterns
• Blaschko lines are consistently V-shaped on the upper spine, S-shaped on the abdomen, inverted U-shaped from the breast area to the upper arm, and perpendicular down the front and back of the lower extremities
  • they never cross the anterior truncal midline but run along it. These lines are invisible but many inherited and acquired diseases of skin manifest themselves according to these patterns creating the visual appearance of these lines
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• they do not correspond to nervous, muscular, or lymphatic systems
• can be observed in other animals such as cats and dogs
• German dermatologist Alfred Blaschko is credited for the first demonstration of these lines in 1901
  
  
• Many inherited and some acquired skin conditions are distributed along Blaschko lines

  • 	Congenital Disorders
    X-linked dominant skin disorders	Incontinentia pigmenti Focal dermal hypoplasia CHILD syndrome MLS syndrome Oral facial digital syndrome Type 1 X- linked dominant chondroplasia punctata
    Epithelial naevi	Inflammatory linear verrucous epidermal naevus Sebaceous naevus Non-organoid epidermal naevus
    Pigmentary disorders	Naevus achromicus (including hypomelanosis of Ito) McCune-Albright syndrome Segmental vitiligo

   

  • 	Acquired disorders
    Disorders with polygenic background	Linear lichen planus Linear cutaneous lupus erythematosus Lichen striatus Linear morphoea

Reference:

• Blaschko's lines- Wikipedia, the free encyclopaedia
• Textbook of Dermatology .Ed Rook A, Wilkinson DS, Ebling FJB, Champion RH, Burton JL. Fourth edition. Blackwell Scientific Publications.